[Protein kinase activities associated with actin cytoskeleton in the oocytes and eggs of African clawed frog]. / Proteinkinaznye aktivnosti, assotsiirovannye s aktinovym tsitoskeletom v ootsitakh i iaitsakh shportsevoi liagushki.

Protein phosphorylation with specific protein kinases plays the key role in the regulation of meiotic maturation of oocytes. However, little is known about the contribution of kinases to the temporal and positional regulation of the cytoskeleton rearrangement in maturing oocytes, including the actin cytoskeleton. In order to study a relationship between the kinase activities and actin cytoskeleton rearrangement, we analyzed protein phosphorylation in the isolated actin cytoskeleton of Xenopus laevis oocytes. Analysis of the full grown oocytes and eggs injected with [gamma-32P] "P has revealed phosphorylation of many proteins associated with the actin cytoskeleton and shown the appearance of three additional major phosphoproteins, 20, 43, and 69 kDa, during oocyte maturation. A significant number of these phosphoproteins were also found after incubation of the isolated cytoskeleton with [gamma-32P] "P in vitro, thus confirming that the kinases modifying these substrates are also specifically associated with actin. The in vivo and in vitro kinase activities were also stimulated during maturation. Analysis of kinase self-phosphorylation in situ and protein phosphorylation in solutions and substrate containing gels revealed a set of actin-associated kinases, including cAMP- and Ca(2+)-dependent kinases, as well as MAP, p34cdc2, and tyrosine kinase activities. Their level was the highest in the eggs. The involvement of kinases in the actin cytoskeleton rearrangement during oocyte maturation is discussed.

[The effects of exogenous actin-binding casein kinase injected into the oocytes and ova of the clawed toad]. / Effekty ékzogennoi aktinsviazyvaiushchei kazeinovoi kinazy, in''etsirovannoi v ootsity i iaitsa shportsevoi liagushki.

The effects of microinjections of exogenous casein kinase 2 on the structural organization of the maturing oocytes and eggs were studied in Xenopus laevis. Kinase inhibited the progesterone-stimulated oocyte maturation and induced dislocation of pigment granules. The morphological effect was shown to be dose-dependent. The results obtained are discussed in the light of the possible influence of casein kinase 2 on the organization of the cortical actin cytoskeleton through phosphorylation of actin-binding proteins.

[Actin-binding proteins in Xenopus laevis oocytes and eggs. I. Presence and distribution of alpha-actinin and vinculin]. / Aktinsviazyvaiushchie belki v ootsitakh i iaitsakh shportsevoi liagushki. I. Prisutstvie i raspredelenie alpha-aktinina i vinkulina.

We studied the distribution of two actin-binding proteins, alpha-actinin and vinculin, in the oocytes and eggs of Xenopus laevis. These proteins are localized in the cortical area. A morphological connection of vinculin with the mirofilaments and plasma membrane was shown; the actin matrix in the egg was gold-labeled more intensely than in the oocyte. A possible role of these proteins in development of the cortical contractility and rearrangement of the actin cytoskeleton during oocyte maturation is discussed.

[The morphological criteria and proposed mechanisms of cortical contractility in oocytes of the clawed toad]. / Morfologicheskie kriterii i predpolagaemye mekhanizmy kortikal'noi sokratimosti ootsitov shportsevoi liagushki.

It is proposed to consider certain states of the cortical actin cytoskeleton corresponding to various stages of oocyte maturation as morphological criteria of the cortical contractility during progesterone-induced oocyte maturation. In the definitive oocyte, the cortical microfilaments form an anisotropic network, while in the mature egg, they form an isotropic disorganized network and, at the moment of contraction, bundles. Factors of the actin cytoskeleton transformation are discussed: actin-binding proteins, protein kinases, and bivalent ions. The data are given on the presence and distribution of the actin-binding protein vinculin in the cortex of the oocyte.

[A morphological study of the keratin cytoskeleton of the oocyte from the clawed toad using heterologous monoclonal antibodies]. / Izuchenie morfologii keratinovogo tsitoskeleta ootsita shportsevoi liagushki s pomoshch'iu geterologicheskikh monoklonal'nykh antitel.

Heterologous monoclonal antibodies E2 (against rat cytokeratin 8) and OSC-1 (against cytoskeletal preparations of mouse oocytes) were used to study the presence and distribution of cytokeratins in Xenopus oocytes during their maturation and growth. To improve visualization of cytokeratins, more adequate methods of oocyte fixation and processing were developed. The results on distribution of cytokeratins obtained with the above mentioned antibodies were compared with one another and with published data. It was found that data obtained by different authors, who used different types of antibodies and different methods for fixation and visualization of Xenopus oocyte cytokeratins, are often contradictory and inconsistent. Along with that, common features of cytokeratin distribution are revealed that have been noticed by every author: animal-vegetal asymmetry of cytokeratin distribution and the existence of two keratin domains, cortical and ooplasmic ones. Specific for the cortical domain of the animal hemisphere is the arrangement of filaments in parallels to the surface, whereas filaments of the ooplasmic domain are oriented radially. The vegetal hemisphere is characterized by the presence of a network formed by filaments with different orientation. We also describe certain peculiarities of cytokeratin distribution in previtellogenic oocytes, as well as disintegration of the keratin system by the end of oocyte maturation.

[The participation of polymerized actin in maintaining the spatial organization of the oocyte in the clawed toad and its detection in the deep regions of the ooplasm]. / Uchastie polimerizovannogo aktina v podderzhanii prostranstvennoi organizatsii ootsita shportsevoi liagushki i ego vyiavlenie v glubokikh oblastiakh ooplazmy.

Microfilaments were shown to be involved in maintaining spatial organization of the Xenopus laevis oocyte by using injections of DNAse I, which selectively destroys F-actin. An original method has been proposed for visualization of polymerized actin at the electron microscope level. Standard histological sections (5-6 um) were deparaffinized, treated with gold-labelled phalloidin, dehydrated, and embedded in epoxy resins using gelatin capsules placed onto sections. After resin polymerization, the section separated from the slide in liquid nitrogen was cut in ultrathin sections on an ultratome. This method allows to by-pass the cutting on an ultracryotome and to study the distribution of polymerized actin in any region of the oocyte at the electron microscope level. The method allows to make the light immunohistochemistry data more precise. We have shown using this method the presence of F-actin not only in the cortex, as was established earlier, but also in deep layers of the ooplasm. Some aspects of the intracellular matrix organization are discussed.

[Contractile proteins and nonerythroid spectrin in the oogenesis of the clawed toad]. / Sokratimye belki i neéritroidnyi spektrin v oogeneze shportsevoi liagushki.

Distribution of contractile proteins, actin and myosin, and spectrin was studied in oogenesis of X. laevis. These proteins are present already at the previtellogenic stages, where they are diffusely distributed. During vitellogenesis actin and myosin are distributed in the animal region in a fibril-like way, while in the vegetal one they are concentrated around the yolk platelets. In the mature oocyte, distribution of actin and myosin again becomes diffuse. Spectrin forms in the vitellogenic oocyte a network all over the cytoplasm, while in the full-grown oocyte it is localized mostly in the subcortex of the animal region and disappears during oocyte maturation. All these proteins are present in the nuclei of oocytes. Changes in distribution of actin, myosin and spectrin during oocyte maturation are discussed with reference to the cortical contractility, spatial distribution of yolk platelets and regional sensitivity to cytochalasin B.

[The distribution and relation to the cytoskeleton of specific prosomal proteins in the oogenesis of the clawed toad]. / Raspredelenie i sviaz' s tsitoskeletom spetsificheskikh prosomnykh belkov v oogeneze shportsevoi liagushki.

Using immunoblotting and immunofluorescent microscopy, we showed the presence in Xenopus laevis oocytes of two prosomal proteins (27 and 31-33 kDa) and studied their distribution during oogenesis. In the ooplasm, both proteins are detected in prosomal clusters of various size. During previtellogenesis, prosomal proteins are diffusely distributed in the nucleoplasm and form evenly distributed clusters in the cytoplasm. During oocyte growth, prosomal proteins disappear from the nucleus and form animal-vegetal and cortical gradients in the cytoplasm. In the course of oocyte maturation prosomal clusters become smaller. After artificial activation of the egg, the dorso-ventral gradient of distribution of prosomal proteins is observed. Double immunohistochemical labeling revealed morphological association between prosomal clusters and fibril-like structures of the oocyte containing actin and myosin. The latter are then replaced by diffusely distributed actin and myosin. Thus, correlation is observed between localization of the acto-myosin complex of the oocyte and that of prosomal proteins.

[Duration of the mitotic cycle at the period of synchronous cleavage division (t0) in the starfish Asterina pectinifera (Müller et Troschel)]. / Prodolzhitel'nost' mitoticheskogo tsikla v period sinkhronnykh delenii drobleniia (t0) u morskoi zvezdy Asterina pectinifera (Müller et Troschel).

The duration of a single division (tau 0) in a period of synchronous cleavage, time of development before the start of cleavage, and rotation, hatching and gastrulation stages in A. pectinifera at different temperatures were estimated. The range of temperatures optimal for embryonic and early larval development of the starfish was determined.

[Transplantation of nuclei into mammalian ova]. / Peresadka iader v iaitskletki mlekopitaiushchikh.

A review of experimental studies of nuclear transplantation in mammals. The possibility of parthenogenesis in mammals is discussed on the basis of the results reviewed. Discrepancies in the data obtained by different authors are also discussed.

[Fusion of germ and embryonic cells and the prospects of using the somatic hybridization method in embryology]. / Sliianie polovykh i émbrional'nykh kletok i perspektivy ispol'zovaniia metoda somaticheskoi gibridizatsii v émbriologii.

The role of investigations in which the method of induced cell fusion was used in studying the oocyte maturation, fertilization and early embryogenesis of animals has been analyzed on the basis of the published and the authors' data. The problems of developing the method of induced cell fusion, its combining with the other experimental methods (microsurgery, cell fragmentation, etc.) and the perspectives of its using in embryology are discussed.